electrical shop in a ship repair yard.pdf

8/10/2019 electrical shop in a ship repair yard.pdf

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SEMINAR REPORT

SHIP PRODUCTION II

Electrical Shop in a Ship Repair Yard

10-October,2012

Submitted by:

Naseef PK

Nikhil KR

Rashid K

Mohammed Nizar PMSemester-VII

B.Tech in Naval Architecture

and Shipbuilding

DOST, CUSAT


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ELECTRICAL REPAIR SHOP

The electrical shop in a ship repair yard should be equipped and capable of

undertaking repairs and rewinding of full range of motors and generators of ships

and overhaul of electrical apparatus and switch gears. List of major equipments

here are:-

Electric Coil Winding machines

Industrial Furnaces

Dimmer stats

Quick way Armature winding machine with counter

Coil winding machinery with counter

Testing panel with dimmer stat

The potential for electrical shock hazards is greater in shipbuilding and repairthan in other industries, because workers stand on metal decks and often work in a wet

environment. Work on or around energized electrical equipment can expose workers

to electrocution, burns, or electrical shock. Before work is performed, energized

equipment must be guarded, de-energized, or appropriate PPE used to prevent worker

exposure.


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ELECTRICAL SHOP PLAN


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MAINTENANCE AND INSPECTION OF ELECTRICAL EQUIPMENT ON

THE SHIP

The electrical switchboards, section boards and their equipment, on board the ship, are

generally subjected to structural, climatic or electrical wear. In order to preserve their

integrity throughout the ship's life, it seemed necessary to develop recommendations

dealing with their maintenance and inspection.

Actions EVERY EVERY FIVE

YEAR YEARS

1. Electrical switchboards and section boards are to be visually X X

examined to assess the good operation and maintenance.

2. Electric equipment is to be examined for cleanliness. Where X X

deemed necessary, cleaning of electrical equipment.

(dust suction, wiping up oil water deposits)

3. It is to be checked that:

3.1 Cables or other electric equipment are still in the original X X

position. Any modification should be to the satisfaction

of the Society.

3.2 Cable penetration devices are still in good condition X X

3.3 No evidence of overheating, burning or tracking X X

3.4 Measuring equipment is in order. X X

3.5 Mechanical ventilation, if fitted, operates as required X X

3.6 Where a protection device has been replaced, its rating and, X X

where applicable, settings are to be verified.

4. Contacts and arc screens, if any, of all concerned devices are X

to be checked and reconditioned or replaced if necessary in

accordance with manufacturers recommendation.

Movable parts of the said devices are to be tested.

5. Tightening of connections and assemblies which may slacken X

is to be checked and tightened, if required, according to the

manufacturers recommendations. Thermograph aids may

be considered to detect hot spots.

6. Where accumulator batteries may be stored, the condition of X X

connections (salt deposits ...), the fastenings, the ventilation


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and the tray tightness are to be checked.

7. Where fitted, computer based systems are to be tested. X

Their original functions are to be unchanged.

8. An insulation measurement of any circuit in doubt is to be X

carried out. Any large decrease in values is to be

investigated and corrected.

9. All circuits are to be subject to insulation measurements for X

comparison with the insulation recordings previously

established. Corrective actions are to be carried out if the

values obtained are under 1k per volt.

10. Circuit interlocks, if any, are to be tested. X

11. Protective devices are to be tested. The electronic protective X

devices for generators and large consumers are to be tested

12. The operation of all emergency sources of power is to be tested, X X

including their automatic devices if any.

13. All automatic sequences, e.g. for synchronization, connection, X X

load shedding if any are to be tested as far as practicable.


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PROCESS FLOW FOR GENERATOR/MOTOR REPAIR

Identification of physical damage

Insulation check

Opening meeting between

representatives of yard and owner

Handing over of work to Electric

shop

Dismantling of parts

Re-check for damage

Cleaning of parts. Mainly fresh

water rinsing. If oil present, apply

chemicals.

Baking process done in OVENS

Apply varnish and check the

readings

Assemble the parts

Computerized checking of every

parameters

Curing period: Sometimes

need BAKING

Apply coating (eg: BETTOL)Advantage of usingBETTOL

Insulation

Anti-corrosive

Installation of Machinery


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MAIN SWITCH BOARD

One more important thing is the main switch board. All the machineries on ship that

consume electrical power should be connected to a main switch board. The system

should be designed in such a way that under all normal conditions of operation, power

should be distributed from main switch board.

The main switch boards are located in the center of the distribution or in engine

control room. They should be installed in such an area that in time of emergency such

as fire or flooding, they should be easily accessible. Thus they should be installed in

spaces away from the main machinery spaces.

In general a MSB should have the following boards,

1. 220V FEEDER PANEL

2. GROUP STARTER PANEL-2

3. 440V FEEDER PANEL-2

4. GEN-3 PANEL

5. TIE BREAKER & ESB BREAKER

6. SYNC PANEL

7.

GEN-2 PANEL

8.

GEN-1 PANEL9.

440V FEEDER PNL-1

10. GROUP STARTER PANEL-1


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ELECTRICAL DIAGRAMS

Different types of diagrams used in the ships and shop involves,

BLOCK DIAGRAM

SYSTEM DIAGRAM

CIRCUIT DIAGRAM

WIRING DIAGRAM

CONNECTION DIAGRAM

Block diagram

The block diagram is typically used for a higher level, less detailed description aimed

more at understanding the overall concepts and less at understanding the details of

implementation. In electrical engineering, a design will often begin as a very high

level block diagram, becoming more and more detailed block diagrams as the design

progresses, finally ending in block diagrams detailed enough that each individual

block can be easily implemented (at which point the block diagram is also a schematic

diagram). This is known astop down design.Geometric shapes are often used in the

diagram to aid interpretation and clarify meaning of the process or model. The

geometric shapes are connected by lines to indicate association and direction/order oftraversal. Each engineering discipline has their own meaning for each shape.

System diagram

The system diagram shows connections between different systems involved. It helps

the engineer to understand different interconnections between the systems. It also

helps to identify the corrections required when the problem is identified.

Circuit diagram

A circuit diagram (also known as an electrical diagram, elementary diagram,

or electronic schematic) is a simplified conventional graphical representation of

anelectrical circuit.Apictorial circuit diagram uses simple images of components,

while aschematic diagram shows the components of the circuit as simplified standard

symbols; both types show the connections between the devices,

includingpower andsignal connections. Arrangement of the components

interconnections on the diagram does not correspond to their physical locations in the

finished device. Unlike ablock diagram orlayout diagram,a circuit diagram showsthe actual wireconnectionsbeing used. The diagram does not show the physical

arrangement of components.
http://en.wikipedia.org/wiki/Top-down_and_bottom-up_designhttp://en.wikipedia.org/wiki/List_of_geometric_shapeshttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Pictorialhttp://en.wikipedia.org/wiki/Schematic_diagramhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Signal_(information_theory)http://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/wiki/Integrated_circuit_layouthttp://en.wikipedia.org/wiki/Electrical_connectionhttp://en.wikipedia.org/wiki/Electrical_connectionhttp://en.wikipedia.org/wiki/Integrated_circuit_layouthttp://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/wiki/Signal_(information_theory)http://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Schematic_diagramhttp://en.wikipedia.org/wiki/Pictorialhttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/List_of_geometric_shapeshttp://en.wikipedia.org/wiki/Top-down_and_bottom-up_design


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Wiring diagram

A wiring diagram is a simplified conventional pictorial representation of an electrical

circuit. It shows the components of the circuit as simplified shapes, and the power and

signal connections between the devices. A wiring diagram usually gives more

information about the relative position and arrangement of devices and terminals on

the devices, to help in building the device. This is unlike aschematic diagram wherethe arrangement of the components interconnections on the diagram does not

correspond to their physical locations in the finished device. A pictorial diagram

would show more detail of the physical appearance, whereas a wiring diagram uses a

more symbolic notation to emphasize interconnections over physical appearance.

Connection diagram

The detailed connections that have to be made are indicated in this diagram. Each andevery specification must be included in this diagram regarding connections.
http://en.wikipedia.org/wiki/Schematic_diagramhttp://en.wikipedia.org/wiki/Schematic_diagram


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TESTING

INSULATION RESISTANCE (MEGGER)

The insulation resistance (IR) test (also commonly known as a Megger) is a spot

insulation test which uses an applied DC voltage (typically either 250Vdc, 500Vdc or

1,000Vdc for low voltage equipment


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CURRENT (CLAMP METER)

Clamp meters are a very convenient testing instrument that permits current

measurements on a live conductor without circuit interruption. When making current

measurements with the ordinary multimeter, we need to cut wiring and connect the

instrument to the circuit under test. Using the clamp meter, however, we can measurecurrent by simply clamping on a conductor as illustrated in Fig.2. One of the

advantages of this method is that we can even measure a large current without shutting

off the circuit being tested.

VOLTAGE (MULTIMETER)

A multimeter is very useful in measuring and testing DC voltage. The

multimeter can be a standard multimeter, a digital multimeter (DMM), or a

auto-ranging digital multimeter. The source of the DC voltage can be from

batteries, circuits, transformers, or any other electronic device that operates on

DC voltage. Troubleshooting of DC electronics is made easier by using a

digital multimeter to test in-circuit DC voltage and compare the results to an

electrical schematic. Faulty components can be identified within the circuit in

order to make repairs.


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RESISTANCE (MULTIMETER)

An ohmmeter can be used to directly measure an unknown resistance R .This is

the simplest way to measure resistance. It is important to realize that an

ohmmeter cannot be used when the resistance is connected in a circuit and acurrent is flowing through it .

CONTINUITY (MULTIMETER)

One of the most basic uses of a multimeter is to test for continuity. Testing for

continuity basically means testing to see if there is an electric connection

between two points. If two points are electrically connected they are said to be

continuous. This brief guide explains how to use a digital multimeter to findout if there is an electric connection between two points.


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INSULATION CLASS

Electrical insulation is classified with its maximum allowable temperature. By

adopting an insulation technique of higher thermal endurance, electric instruments can be

downsized. In early times, the temperature classes of electric insulators were simply divided

into natural organics, inorganics, and combinations thereof. In the late 1930s, the types of

synthetic resins became diverse and their production volumes increased, with theirapplication range being gradually expanded to insulation. In the late 1940s, when silicone

resin became a popular insulator material, the H-class insulator was added to the temperature

classes, and it became increasingly necessary to find applications for heat resistant materials

in electric instruments.

CLASS YWithstands a temperature of up to 90C; typically made of cotton, silk, or paper.

e.g.: Cotton, silk and paper.

CLASS A

Withstands a temperature of up to 105C; reinforced Class-Y materials with

impregnated varnish or insulation oil.

e.g.: Cotton silk and paper all suitably impregnated or coated with oil or other

insulating compound.

CLASS E

Withstands atemperature of up to 120C.e.g.: Mica, asbestos and glass products all organic bounding substances.

CLASS B

Withstands a temperature of up to 130C. This has a form that inorganic

material is hardened with adhesives. This is the first insulator using this structure.e.g.: Mica, asbestos and glass products all with suitable bonding.

CLASS F

Withstands a temperature of up to 155C; for example, made of Class-B

materials that are upgraded with adhesives, silicone, and alkyd-resin varnish ofhigher thermal endurance.

e.g.: Mica asbestos and glass products all with inorganic bonding substances.

CLASS H

Withstands a temperature of up to 180C; for example, made of inorganic

material glued with silicone resinor adhesives of equivalent performance.e.g.: Mica, glass fibre, asbestos, silicon all with silicone as bonding material.

CLASS CWithstands a temperature of up to 180C or higher; made of100% inorganic

material.e.g.: Mica, porcelain, glass, quartz all with or without inorganic bonding material.


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PROTECTION CLASSDENOTED AS IP XY

Ingress Protection rating is used to specify the environmental protection - electrical enclosure

- of electrical equipment.

Ingress Protection (IP) ratings are developed by the European Committee for Electro

Technical Standardization (CENELEC)(NEMA IEC 60529 Degrees of Protection Provided

by Enclosures - IP Code), specifying the environmental protection the enclosure provides.

The IP rating normally has two (or three) numbers:

1.Protection from solid objects or materials

2.Protection from liquids (water)

Protection against mechanical impacts (commonly omitted, the thirdnumber is not a part of IEC 60529)
http://www.cenelec.org/http://www.cenelec.org/


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MOTOR STARTERS

CAGE MOTOR

DIRECT ON LINE

DOL STARTER CONTROLSCHEMATIC DIAGRAM

STAR/DELTA


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AUTOTRANSFORMER


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ELECTRICAL SURVEY REQUIREMENT

GeneratorsA generator is a simple device to convert mechanical energy into electrical energy. Usually

they generate rotating current 50Hz or 60Hz leaving for direct-driven machines of the

following engine speeds of 500/600 RPM, 6001720RPM, 750/900 RPM, 100011200RPM,

1500/1800 RPM and 3000/3600RPM. The higher figures are mostly for smaller generatorsets or turbine driven machines.

Electric motorsElectric motors are simple devices to convert electrical energy into mechanical energy. AC

squirrel cagemotors have the same RPM restriction as AC generators. Motors area available

in different casings for fitting on a foundation or flange for fitting to a pump. Also various

protection classes against the ingress of solid particles and water area available, and for use in

an explosive

Environment increased safety "non sparking types" and flame proof motors are available.

CablesCables form the connections between the different parts of the electric installation and are

nowadays available as low-smoke , low toxic and even fire-resistant types. Application of

such more sophisticated cables will reduce the consequences and damage of a fire. The

commercially attractive PVC insulated types are vulnerable in case of fire. The insulation

burns causing short circuits. They generate high quantities of toxic and corrosive gases which

will damage a lot more of the installation than that damaged by the fire only. However, a

disadvantage of the low smoke types of cables is that their mechanical properties are

considerably less.

Switchboards and switchgear assembliesSwitchboards and other switchgear assemblies basically serve to connect and disconnect

generators and consumers to the main power supplysystem. They contain also theprotection

devices of the generators, the cables and the consumers against overload and short-circuits.

Switchboardsand other control-gear assembliescan be operated by engineers, but servicing

and maintenance and repairs should be carried outbyspecialists.Laws in most countries issue

a clearinstruction of how to power apart of an installation safely, to carry out

repairsand power up safely afterwards. It also defines skills andresponsibilities of the

operators andmaintenance people. The main differencesbetween an industrial switchboard

and a marine switchboard areprotection class IP23 with closed doors. In case of open doors,

protection class lP20, handrails, door catchersin open position, measuring andindicationinstruments to be able to

synchronise and for load sharingofboth power and current etc.

When electricpower is required forpropulsion of the ship, the source of

power is to be duplicated and the mainbus basin the main switchboard

is to be divided in two parts connected by a removable link for small

installations up to full-size circuit breakers with selective protection devices for large

installations. Duplicated essential consumers shallbe supplied each from a side of the switch

board,or when supplied from distribution-boards from separate

distribution-boards, each supplied from a side of the main switchboard.All of this with the

same target that a single fault does neither impair thepropulsion system nor impair

thehabitability for the crew. This single failure also includes a fire or other damage to a cabletray. Therefore thepower cables and control cables toessential duplicated consumers shall be

separated.


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Circuit breakers and contactorsA circuit breaker is designed to close and interrupt a short-circuit current a few times only

without maintenance.A contactor is designed to withstand thousands of times the starting

currents of electric motors. A circuit breaker is therefore not suitable tostart a large motor.

Switching capabilitiesare given under different conditions. Some manufacturers give a

capacity only oncepossible.

Moulded case circuit breakers, especially the current limiting types can be replaced as a

complete unit only.

Emergency generatorAn emergency generator is a generator with the same characteristics as a main generator but

located in a space separated from the main generators and independent of any equipment

outside this space. So starting equipment such as an air bottle with a non-return valve of the

engine room starting air system, a

separate fuel tank, an emergency switchboard in the same space as the generator set to limit

the possibility of failure of the emergency system in case of failure of a space, This all to

ensure continuity of emergency power as much as possible

Starting devicesStarting devices are used to limit the in-rush current of a consumer when connected to the

main power supply to an acceptable value. That is to a value that does not disturb the proper

functioning of the other devices in the installation. Starting devices are also used to limit the

starting torque of an electric motor.


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HAZARDOUS AREAS

Dangerous areas are those areas where due to the continuous or part time

presence of gases or flammable liquids or even explosive dust, the risk of explosion exists.

Dangerous areas are, for example, the tanks of a tanker and the deck above, the cargo-handling area, pump room etc..but also the car-deck of a ferry where cars are stowed with

fuel in their tanks, a helicopter refilling station on a yacht and a paint store or the hold of a

dry-cargo ship certified for the carriage of dangerous goods.

Cost-effective solution number one is not to install any electrical equipment

In dangerous areas. The dangerous areas are divided into the following

zones:

Zone 0Areas where an explosive-gas atmosphere is continuouslypresent or Canbepresent. For

example, a cargo tank of a crude oil tanker, oil productstanker or chemical tanker carrying flammable liquids other than liquefiedgases having a nash

point not exceeding 60C and for liquefied gases the cargo tank and the secondary barrier

spaces.

Zone 1Areas where an explosive-gas atmosphere will be periodically present during normal

operation. For example, spaces adjacent to andbelow the top of the cargo tanks carrying

crude oil, oilproducts etc. with a flash point not

Exceeding 60C.Spaces separatedby a single deck orbulkhead from zone 0 areas, also cargo

pump rooms and enclosed and semi-enclosed spaces in which pipes containing above cargoes

are located. Also areas on open deck within 3 metres of any cargo tank outlet, cargo valve,

cargo-pipe flange, cargo-pump room outlets, 6 metres radius from highpressure discharge

valves and 2.4 metres above deck

.Zone 2Areas where an explosive gas atmosphere is not present during normal operation and. if

present, for a short period of time for tankerscarrying products with a flash pointabove

60C.This is the only zone defined for the dry-cargo ships and for Ro/Ro spaces of ferries if

sufficiently ventilated. The explosive-gas atmosphere is considered not tobepresent during

normal operation.

Caution: Liquified natural gas (LNG) and the vapours from kerosine are heavier than air andany opening to a deck or lower space shall be subject to further study with respect to the

zoning. The gases are divided into the following groups:

- Group I: methane such as expected in coal mines

- Group II: General industrial gases and gases from combustible liquids and combustible

solids

- Group IIA: Propane

- Group IIB: Ethylene

- Group IIC: Hydrogen

Apart from the gas group, certified safe equipment shall also be selected on the basis of the

maximum surface temperature during operation. This surface temperature shallbe below the

ignition temperature of the gas emittedby the cargo as is stated in the cargo lists.Temperature classes and maximum surface temperatures are as follows:


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TI below 450C

T2 300C

T3 200C

T4 135C

T5 100C

T6 85C

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